The objectives of this investigation are: (1) to understand the relationship between microstructure of dental amalgams and their creep and corrosion behavior and (2) to clarify the roles of creep and corrosion in the marginal breakdown of dental amalgams. The methodology involved the determination of the creep and corrosion behavior of dental amalgams as a function of the volume fractions of various microstructural phases, namely, Ag3Sn (gamma), Ag2Hg3 (gamma 1), Sn7Hg (gamma 2), and Cu6Sn5 (eta), present in dental amalgams. The results obtained so far indicate that the creep resistance of a dental amalgam is adversely affected by the presence of both gamma 1 and gamma 2 whereas beneficial effects on creep resistance result from the presence of gamma and Cu6Sn5. The corrosion resistance of a dental amalgam, on the other hand, is impaired by the presence of gamma 2 and/or Cu6Sn5. These results appear to explain the reported marginal integrity of clinical amalgam restorations while at the same time reinforcing the hypothesis that corrosion is mainly responsible for the marginal breakdown of dental amalgams, with or without the gamma 2 phase.